An athermalized secondary imaging system for a mid-wave infrared Fourier transform imaging spectrometer

Abstract

An athermal difference secondary imaging system for a mid-wave infrared Fourier transform imaging spectrometer, which relates to the field of spectral imaging technology and solves the shortcomings of the existing infrared optical system athermal difference technology, including stepped micro-mirrors, beam splitters, and compensation plates , five lenses, a detector window, a detector cold stop and a detector front; the present invention solves the power distribution equation, the system defocus equation and the material thermal expansion and lens barrel thermal expansion equations caused by the change of the refractive index of the lens, using The three materials of chalcogenide glass, germanium and silicon are combined with each other to realize the passive heat dissipation function. The system realizes the passive adiabatic function in the temperature range of -20°C-60°C, the relative illumination at the edge of the image plane is close to 90%, the distortion is less than 0.4%, the passivation value at 17lp / mm is close to the diffraction limit, and the depth of field of the system satisfies The total height of the step mirror, the design results show that when the object plane is imaged at different step height positions, the maximum change rate of the system MTF value does not exceed 1%. The system achieves 100% cold stop matching without vignetting.

Description

technical field [0001] The invention relates to the technical field of spectral imaging, in particular to a space-time combined modulation type Fourier transform imaging spectrometer athermal difference secondary imaging system working in mid-wave infrared and based on stepped micro-reflectors. Background technique [0002] The vast majority of VOCs gases have obvious characteristic absorption peaks in the mid-wave infrared spectrum. Spectral analysis of them by spectroscopic instruments can quickly identify the type and concentration of pollutants and other information. Compared with prism and grating spectrometer, the Fourier transform imaging spectrometer has the advantage that the detection spectrum can cover the middle and far infrared bands. However, due to the particularity of infrared materials, temperature changes will change the refractive index of materials, the radius and thickness of optical elements, and the spacing between optical elements, resulting in therma...

AI Technical Summary

Problems solved by technology

[0004] The present invention solves the problem that the existing secondary imaging system is affected by the ambient temperature, difficult to install and calibrate, lack of map information caused by low illumination at the edge of the image plane, and the inability to obtain full-frame clear images caused by the system depth of field being smaller than the total height of the stepped micro-mirror. Problem: Provide a kind of mid-wave infrared Fourier transform imaging spectrometer athermal difference secondary imaging system

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